Porokeratosis is a group of disorders with distinct clinical feature of hyperkeratotic papules or plaques surrounded by an elevated, thread-like border, as well as pathological feature of cornoid lamella. Several variants of porokeratosis have been recognized, most of which follow a chronic and progressive disease course. However, there exists a rare variant characterized by a relatively rapid evolving and disseminated clinical course. The term “eruptive disseminated porokeratosis (EDP)” was proposed in the literature to describe this atypical form of porokeratosis.[1]

Case Report

A 73-year-old woman presented severely itchy skin rashes on trunk and extremities for 9 months. The eruptions initially flared up as scattered pruritic lesions on the arms and legs and then disseminated to a greater extent in the following weeks. No similar condition ever occurred on the involved sites before, nor any specific episode such as fever or new drugs exposure preceded. The eruptions persisted for months without resolution despite prescribed topical and oral medications.

On physical examination, multiple brownish to erythematous, various sized papules were noted on the trunk and four limbs [Figure 1]a and [Figure 1]b, with some lesions showing a slightly elevated rim. Excoriation and prurigo-like lesions also presented. Skin biopsies were performed on the right arm [Figure 1]c and left arm, respectively. Histopathology examination revealed superficial perivascular lymphocytic infiltration and cornoid lamella in both specimens [Figure 2]. Based on the rapidly evolving, disseminated, and symptomatic clinical course as well as pathological findings, EDP was diagnosed.

Limited therapeutic response was observed following oral antihistamine agents and topical/intramuscular steroid; neither disease regression was noted after weeks of follow-up. Due to severely bothering itchiness (visual analog scale [VAS]: 8/10) complaint by the patient, therapeutic attempt with liquid nitrogen cryotherapy (3 s each selected lesion) was performed to relieve the symptom. A quite satisfactory outcome (VAS: 1/10 for treated lesions) without significant complication was obtained by 2–3 sessions of therapies with a 2-week interval. An average of 15 lesions was treated in each session considering the patient's tolerability, and thus, the total course took months to manage the extensive eruptions. The antipruritic effect persisted throughout the course with minimal rebound, and the patient stated an overall improvement in quality of life after relief of the pruritus.

Discussion

Porokeratosis usually follows a chronic, progressive, and asymptomatic clinical course. However, there are several case reports describing a variant with rapid and disseminated evolution. Different terms were once used by different authors, such as “eruptive pruritic papular porokeratosis,”[2] which highlighted the symptomatic nature of this variant. Shoimer et al. proposed the use of EDP to describe all cases of acute, disseminated eruptions of porokeratosis.[1] EDP is defined as having rapid-onset (<2 months), disseminated lesions (>100 lesions involving multiple regions), and histopathology consistent with porokeratosis. Epidemiologically, EDP occurred predominantly in an older demographic (mean age: 65.8 years), and the male-to-female ratio was approximately 2:1. The lesions of EDP often showed variable morphologies that were uncharacteristic of porokeratosis, most of which may due to pruritus-related manipulation.

A categorization system was also proposed to classify EDP into four subtypes: paraneoplastic, immunosuppressed, inflammatory, and other. About 30% of individuals with EDP were with recently diagnosed malignancy, and the eruptions may regress after treatment of the underlying disease, thus indicating a paraneoplastic syndrome. Another 30% of individuals with EDP were under immunosuppressed state, most of which were therapeutics related. Another 30% of individuals with EDP were with preexisting porokeratosis, especially disseminated superficial porokeratosis (DSP), and was once described as “inflammatory DSP.”[3] The remaining 10% of patients represented an even more rare subgroup of idiopathic disease. The nature of this idiopathic subtype of EDP is unknown due to limited number of case reports, but it seems to be more refractory to treatment and with a tendency to chronicity. One patient reported by Stork and Kodetová showed no disease resolution after follow-up for 16 months,[4] and a similar clinical course was observed in our case, too.

To treat the symptomatic eruptions and improve the quality of life, various interventions were mentioned in previous reports but mostly with limited effects. Oral tretinoin can sometimes be helpful in EDP. In this case, cryotherapy showed a satisfactory result (VAS: 8-1) for the disease-related itchiness and a good cost-effectiveness.

In conclusion, we presented a rare case of idiopathic EDP. To approach such cases, a comprehensive survey should be conducted to rule out possible underlying malignancy and immunosuppressive status. Liquid nitrogen therapy may be considered as a relieving treatment for refractory and debilitating pruritus.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.